.NET 6.0 enabled by default in master branch

[JohnSchmeichel]

.NET Core 3.1 has reached end of life as of December 13, 2022, so the install scripts have been updated to default to the .NET 6.0 version.

For Windows users can opt into the .NET Core 3.1 version with:

iex "& { $(irm https://aka.ms/install-artifacts-credprovider.ps1) } -InstallNet6:`$false"

And for Linux/Mac users can opt into the .NET Core 3.1 version with:

curl -fsSL https://aka.ms/install-artifacts-credprovider.sh | USE_NET6_ARTIFACTS_CREDENTIAL_PROVIDER=false bash

Note that .NET Core 3.1 has reached end of life and will be removed in future versions of the credential provider.